1. Field of the Invention
The present invention relates to a PDCCH transmission method and system for bandwidth aggregation in a wireless mobile communication system. More particularly, the present invention relates to the PDCCH transmission method and system with a design of DCI format of PDCCH carrying resource allocation information for supporting bandwidth aggregation in an LTE advanced system.
2. Description of the Related Art
In order to meet the high data rate requirement of IMT-Advanced (International Mobile Telecommunication-Advanced), it is necessary for a mobile communication to secure the bandwidth broader than minimum 40 MHz per FA (Frequency Allocation). Although it is necessary for each mobile carrier to be assigned plural FAs to secure the bandwidth equal to or broader than 100 MHz, it is impossible to assign such a broad bandwidth newly to a mobile carrier
Accordingly, various bandwidth aggregation technologies such as the spectrum aggregation for aggregating distant bands or the multicarrier aggregation for aggregating conventional FAs assigned for other services are considered in IEEE 802.16m and 3GPP LTE advanced (3rd Generation Partnership Project Long Term Evolution advanced) system.
Here, the 3GPP LTE Advanced system should fulfill the following requirements. First of all, the 3GPP LTE Advanced base station has to support the legacy LTE terminal in the same frequency bandwidth as well as the LTE advanced terminal by aggregating two or more LTE bandwidths. Also, the LTE advanced terminal has to be able to connect to the conventional LTE base station.
In order to fulfill the requirements of the aforementioned 3GPP LTE Advanced standard, it is necessary to modify the Downlink Control Information Format (DCI) carried in Physical Downlink Control Channel (PDCCH).
For this purpose, it can be considered to transmit the PDCCH including the resource allocation information in unit of basic bandwidth of the LTE system (20 Mhz in the drawing) as shown in FIG. 1a. In case that multiple LTE bandwidths are allocated to a terminal as the second terminal (MS2 assumed as LTE advanced terminal), the resource allocation information is transmitted in PDCCHs of the respective bandwidths. Accordingly, the second terminal acquire the information on its data channels transmitted in the respective bandwidths by decoding all the PDCCHs and receives the corresponding data. In such conventional method, the LTE advanced terminal must decode all the PDCCHs always. This increases the complexity of the terminal and power consumption.